With the growing awareness of environmental protection, many countries are dedicated to development of an environmentally clean energy source, such as wind/solar electric power generation. In addition, because the majority of the earth surface is covered by oceans, ocean wave energy is also utilized as a source of mechanical energy. However, although the techniques of ocean wave or wind electricity generation have been popularly developed, the facilities to utilize the ocean or wind wave energy for generating an electric power are expensive and bulky.